Best Realtors in Castro Valley, CA (2026 Guide)

By Matthew Martinez

Castro Valley is an unincorporated community of about 66,000 people in central Alameda County, set in the hills and canyons east of San Leandro and north of Hayward. Because it is not a city, Alameda County handles planning and permits, and a Castro Valley agent should know how that changes the questions a buyer asks.

This guide is published by Diamond Real Estate Group, one of the brokerages listed. Our broker is listed first; other agents are in alphabetical order. The order is not a ranking, and inclusion is not an endorsement.

How we chose the agents in this guide

Each agent below met three checks in October 2026:

1. A current California license. We opened each agent’s record on the California Department of Real Estate (DRE) public lookup and confirmed the name, license type (salesperson or broker) and "Licensed" status.
2. A named brokerage. Each agent’s DRE record shows the responsible broker they work under, and it matches the brokerage on their profile.
3. A public profile that names Castro Valley. We opened each agent’s brokerage profile and confirmed it names Castro Valley or the brokerage’s Castro Valley office.

We did not rank agents, and we did not consider sales volume, reviews or awards. Licenses and affiliations change, so verify the license yourself before you sign anything, and interview more than one agent.

Castro Valley housing in numbers

Source: U.S. Census Bureau American Community Survey, as presented by Census Reporter, Castro Valley CDP. Figures are estimates with margins of error.

The Census Bureau estimates the median owner-occupied home value in Castro Valley at about $1.14 million in 2024. That is a survey estimate, not a current sale price. To price a specific home, an agent should use recent sales from the same part of Castro Valley, since a home on the valley floor and one on a canyon or hillside road often sell differently.

Castro Valley settings: valley floor, canyons and hills

A Castro Valley search can include older and mid-century homes near Castro Valley Boulevard and the BART station, newer subdivisions on the surrounding ridges, and larger lots in canyon areas where roads are narrow and terrain is steep. Neighboring unincorporated Fairview, San Lorenzo and Ashland are separate communities, also under County planning. Our neighborhood property comparison and local comparable sales analysis pages cover how settings affect value. For more detail, see our Castro Valley real estate guide.

Costs and rules specific to a Castro Valley purchase

• Transfer tax. The Alameda County Clerk-Recorder charges the county documentary transfer tax at $0.55 per $500 of value ($1.10 per $1,000), about $1,100 on a $1,000,000 sale. The Clerk-Recorder’s list of city conveyance taxes covers eight cities; Castro Valley is unincorporated and is not among them. Confirm the total on your escrow estimate.
• County planning. As an unincorporated area, Castro Valley follows Alameda County plans and zoning. The County posts its general and area plans, and the County Planning Department is the place to ask about additions, ADUs or lot splits.
• HOA and assessments. Some Castro Valley subdivisions have HOAs or special assessments. Our association and assessment costs page explains what to review, and sellers must make a good-faith effort to provide a notice of special tax districts under Civil Code section 1102.6b.
• Fire hazard zones and AB 38. Hillside and canyon areas may carry State Fire Marshal Fire Hazard Severity Zone designations. In High and Very High zones, sellers may need to provide AB 38 defensible space documentation.
• Inspections and insurance. Our inspection and insurance planning page and the natural hazard disclosure report cover fault, landslide and fire questions to raise early.

Castro Valley agents with verified licenses

Matthew Martinez, Diamond Real Estate Group (publisher of this guide)

Matthew Martinez is the Founder, CEO and Managing Broker of Diamond Real Estate Group. He is based in Sonoma County; contact him to discuss a purchase or sale in Castro Valley. Contact Matthew · Broker #01869679 · Diamond Group Estates Inc DBA Diamond Real Estate Group, DRE #02163490

All agents above are licensed under the responsible broker NRT West, Inc. (DRE #01908304), as shown on each DRE record, and appear on the Castro Valley office roster. The broker-licensed agent works as a broker associate. Some DRE records list a legal name that differs from the name the agent uses professionally. Every agent we could verify for this guide works from one brokerage office, so compare them with agents from other brokerages as well.

How to vet a Castro Valley agent

1. Ask how County planning affects the home. For an addition, ADU or lot split, a good agent should know to start with Alameda County Planning rather than a city.
2. Ask for comparables from the same setting. Valley-floor homes near BART, ridge subdivisions and canyon properties should not be priced from the same sales.
3. Ask about road and access questions. For canyon or hillside homes, ask about private road maintenance, access and parking.
4. Ask about fire zone and insurance early. Ask how they handle fire zone disclosures, AB 38 and insurance quotes before you remove contingencies.
5. Request a net sheet. Ask for estimated closing costs including the county transfer tax, HOA transfer fees and any special assessments.
6. Verify the license yourself. Look up the agent on the DRE site and confirm the responsible broker matches the brokerage they name.

Castro Valley questions we hear

Sources & notes

• California DRE public license lookup (individual records linked in the table)
• Census Reporter: Castro Valley CDP (ACS 2024 1-year; commute from ACS 2020–2024 5-year)
• Coldwell Banker Realty Castro Valley office agent roster
• Alameda County Clerk-Recorder: real property transfer tax
• Alameda County general and area plans
• State Fire Marshal: Fire Hazard Severity Zones
• California Civil Code section 1102.6b (Justia)
• License records checked October 2026 on the California DRE public lookup. Last reviewed October 2026 by Matthew Martinez.

Related: Castro Valley real estate guide · Castro Valley home valuation · Alameda County agents guide · 20 tips for choosing a real estate agent

License-status update: the linked California DRE public records were checked November 2, 2026 and showed "Licensed." Public profile research retains the dates stated above. Names on DRE records may differ from public profile names; verify status and brokerage before selecting an agent.